1. Field of the Invention
The invention relates to a mobile telephone and a method of operating the same, and more particularly to a mobile telephone and a method of operating the same both of which make it possible to receive a call, even when a source voltage is lowered.
2. Description of the Related Art
Since a mobile telephone such as a cellular phone is always carried a user, a mobile telephone is designed to include a rechargeable cell, and receive power from the cell.
Such a mobile telephone is usually designed to include a man machine interface (MMI) to show a user residual power of the cell. A mobile telephone is generally designed to display residual power in a display screen with an eye-con.
A mobile telephone is guaranteed to properly operate only in a specific range of a voltage. A mobile telephone usually has upper and lower threshold voltages, and checks residual power between those threshold voltages. The lower threshold voltage is more important than the upper threshold voltage, because if a source voltage becomes lower than the lower threshold voltage, power supplied from a power source will be soon exhausted. Hence, a mobile telephone is usually designed to include an alarm to annunciate a user that a source voltage has become lower than a lower threshold voltage. Such an alarm is comprised of an indication in a display screen or ringing, for instance. Hereinbelow, such an alarm is referred to as a low-voltage alarm.
As is obvious in view of the above, when the low-voltage alarm is made, it is necessary for the above-mentioned mobile telephone to replace the cell with a new one, to supply power to the cell from an external source, or charge the cell. Otherwise, the mobile telephone could not properly operate.
If the mobile telephone is used when a source voltage is lowered in the vicinity of the lower threshold voltage, current consumption is much increased. As a result, the low-voltage alarm may be made even if the mobile telephone is used not so much.
A mobile telephone consumes a current to the greatest degree in call-receiving, call-transmitting and communication. Hence, if communication is made for long time while a source voltage is in the vicinity of the lower threshold voltage, the low-voltage may be made during the communication, or the communication may be compulsively interrupted. Even if communication were made for short time, repetition of such communication would cause the low-voltage alarm much earlier than a stand-by mode in which a mobile telephone is turned on, but communication is not made in the mobile telephone.
Hence, if a source voltage is lowered in the vicinity of the lower threshold voltage, an important call may not be able to be received.
Many attempts have been made to solve the above-mentioned problem.
For instance, Japanese Unexamined Patent Publication No. 4-321323 has suggested a mobile radio-signal transceiver. In the suggested mobile radio-signal transceiver, if a voltage of a cell is detected to have lowered to a predetermined voltage, call-receiving, call-transmitting and communication are all prohibited. By turning an external switch on, the mobile radio-signal transceiver can carry out to receive a call, transmit a call and make communication therethrough again. Then, if a voltage of a cell is detected to have lowered to a predetermined minimum voltage, call-receiving, call-transmitting and communication are all prohibited again.
Japanese Unexamined Patent Publication No. 5-91018 has suggested a mobile telephone designed to be able to receive a call during a predetermined period of time. Specifically, the suggested mobile telephone is comprised of a timer for measuring the lapse of a predetermined period of time, a key through which operation of the timer is controlled, and a switching transistor controlling a power supply to supply electric power to a radio-signal receiver until the predetermined period of time has passed after the timer 8 had started.
Japanese Unexamined Patent Publication No. 7-162955 has suggested a cellular phone which is capable of annunciating a user a time during which the user can make communication through the cellular phone, based on residual power of a cell. Japanese Unexamined Patent Publication No. 10-209953 has suggested a cellular phone which is capable of lengthening a lifetime of a cell. Specifically, call-transmitting and/or call-receiving are(is) selected in accordance with residual power of a cell. When a cell has much residual power, both of call-transmitting and call-receiving are carried out, and a cycle for intermittently receiving a radio-signal is set equal to a normal cycle. When a cell has intermediate residual power, only call-receiving is carried out, and a cycle for intermittently receiving a radio-signal is set slightly longer than the normal cycle. When a cell has small residual power, neither call-receiving nor call-transmitting are carried out, but the fact that there has been a call is merely recorded, and a cycle for intermittently receiving a radio-signal is set much longer than the normal cycle.
However, the above-mentioned problem remains unsolved even in the above-mentioned Publications.
In view of the above-mentioned problem, it is an object of the present invention to provide a mobile telephone and a method of operating the same both of which are capable of receiving an important call with a predetermined telephone number, even when a source voltage is lowered to a lower threshold voltage.
In one aspect of the present invention, there is provided a mobile telephone including (a) an antenna receiving radio signals, (b) a display screen, (c) voltage source, (d) a memory storing telephone numbers therein, and (e) a controller detecting a telephone number out of a radio signal received through the antenna, comparing the thus detected telephone number to the telephone numbers stored in the memory, and determining whether a call associated with the detected telephone number is to be received, even when a voltage supplied by the voltage source is equal to or lower than a predetermined threshold voltage.
It is preferable that the controller detects a voltage supplied by the voltage source at an every predetermined period of time, and displays a present voltage in the display screen.
It is preferable that the controller receives a call, when the call is of one of predetermined telephone numbers, even if a voltage supplied by the voltage source is equal to or lower than a predetermined threshold voltage.
It is preferable that the controller includes first to N-th predetermined threshold voltages to each of which a telephone number detected out of a received radio signal is compared, wherein N is an integer equal to or greater than 2, the memory storing N groups of telephone numbers in association with each of the first to N-th predetermined threshold voltages, the controller receiving a call, if a voltage supplied from the voltage source is equal to or smaller than the M-th predetermined threshold voltage and a telephone number detected out of a received radio signal belongs to M-th group of telephone numbers, wherein M is an integer between 1 and N both inclusive (1xe2x89xa6Mxe2x89xa6N).
It is preferable that the memory stores the numbers of call-receiving and call-transmitting, and the controller determines whether a call associated with the telephone number detected out of a received radio signal is to be received, based on at least one of the numbers of call-receiving and call-transmitting.
For instance, the memory stores a count X defined by the following equation:
X=Sxc3x97A+Rxc3x97B
wherein A indicates the number of call-receiving, B indicates the number of all-transmitting, and S and R are weight coefficients, the controller determines whether a call associated with the telephone number detected out of a received radio signal is to be received, based on the count X.
It is preferable that the memory stores a total period of time during which a call is received or made, for each one of telephone numbers stored therein, and the controller determines whether a call associated with the telephone number detected out of a received radio signal is to be received, based on the total period of time.
There is further provided a mobile telephone including (a) an antenna receiving radio signals, (b) a display screen, (c) a voltage source, (d) a memory storing telephone numbers therein, (e) an interface through which an operator can set a low-voltage mode in which the mobile telephone is allowed to receive a call associated with predetermined telephone numbers, even if a voltage supplied by the voltage source is equal to or lower than a predetermined threshold voltage, and (f) a controller detecting a telephone number out of a radio signal received through the antenna, comparing the thus detected telephone number to the telephone numbers stored in the memory, and determining whether a call associated with the detected telephone number is to be received, when the mobile telephone is set in the low-voltage mode.
It is preferable that the low-voltage mode is set only when a voltage supplied by the voltage source is equal to or lower than the predetermined threshold voltage.
It is preferable that the controller detects a voltage supplied by the voltage source at an every predetermined period of time, and displays a present voltage in the display screen.
It is preferable that the controller receives a call, if the call is of one of the predetermined telephone numbers.
It is preferable that the controller includes first to N-th predetermined threshold voltages to each of which a telephone number detected out of a received radio signal is compared, wherein N is an integer equal to or greater than 2, the memory storing N groups of telephone numbers in association with each of the first to N-th predetermined threshold voltages, the controller receiving a call, if a voltage supplied from the voltage source is equal to or smaller than the M-th predetermined threshold voltage and a telephone number detected out of a received radio signal belongs to M-th group of telephone numbers, wherein M is an integer between 1 and N both inclusive (1xe2x89xa6Mxe2x89xa6N).
It is preferable that the memory stores the numbers of call-receiving and call-transmitting, and the controller determines whether a call associated with the telephone number detected out of a received radio signal is to be received, based on at least one of the numbers of call-receiving and call-transmitting.
It is preferable that the memory stores a count X defined by the following equation:
X=Sxc3x97A+Rxc3x97B
wherein A indicates the number of call-receiving, B indicates the number of call-transmitting, and S and R are weight coefficients, the controller determines whether a call associated with the telephone number detected out of a received radio signal is to be received, based on the count X.
It is preferable that the memory stores a total period of time during which a call is received or made, for each one of telephone numbers stored therein, and the controller determines whether a call associated with the telephone number detected out of a received radio signal is to be received, based on the total period of time.
In another aspect of the present invention, there is provided a method of operating a mobile telephone, including the steps of (a) receiving radio signals through an antenna, (b) storing telephone numbers, (c) detecting a telephone number out of a radio signal received through the antenna, (d) comparing the thus detected telephone number to the stored telephone numbers, and (e) determining whether a call associated with the detected telephone number is to be received, even when a voltage supplied by a voltage source is equal to or lower than a predetermined threshold voltage.
It is preferable that the method further includes the steps of (f) detecting a voltage supplied by the voltage source at an every predetermined period of time, and (g) displaying a present voltage in a display screen.
It is preferable that the method further includes the step of receiving a call, when the call is of one of the stored telephone numbers, even if a voltage supplied by the voltage source is equal to or lower than a predetermined threshold voltage.
It is preferable that the step (d) includes the step of comparing each of first to N-th predetermined threshold voltages to a telephone number detected out of a received radio signal, wherein N is an integer equal to or greater than 2, and further includes the step of receiving a call, if a voltage supplied from the voltage source is equal to or smaller than a M-th predetermined threshold voltage and a telephone number detected out of a received radio signal belongs to the M-th group of telephone numbers, N groups of telephone numbers being in association with each of the first to N-th predetermined threshold voltages, wherein M is an integer between 1 and N both inclusive (1xe2x89xa6Mxe2x89xa6N).
It is preferable that the method further includes the step of storing the numbers of call-receiving and call-transmitting, and wherein a call associated with the telephone number detected out of a received radio signal is determined in the step (e) to be received or not, based on at least one of the numbers of call-receiving and call-transmitting.
For instance, a call associated with the telephone number detected out of a received radio signal is determined in the step (e) to be received or not, based on a count X defined by the following equation:
X=Sxc3x97A+Rxc3x97B
wherein A indicates the number of call-receiving, B indicates the number of call-transmitting, and S and R are weight coefficients.
It is preferable that the method further includes the step of storing a total period of time during which a call is received or made, for each one of telephone numbers stored therein, and wherein a call associated with the telephone number detected out of a received radio signal is determined in the step (e) to be received or not, based on the total period of time.
There is further provided a method of operating a mobile telephone, including the steps of (a) receiving radio signals through an antenna, (b) storing telephone numbers, (c) setting the mobile telephone in a low-voltage mode in which the mobile telephone is allowed to receive a call associated with the stored telephone numbers, even if a voltage supplied by the voltage source is equal to or lower than a predetermined threshold voltage, (d) detecting a telephone number out of a radio signal received through the antenna, (e) comparing the thus detected telephone number to the stored telephone numbers, and (f) determining whether a call associated with the detected telephone number is to be received, when the mobile telephone is set in the low-voltage mode.
It is preferable that the low-voltage mode is set in the step (c) only when a voltage supplied by the voltage source is equal to or lower than the predetermined threshold voltage.
It is preferable that the method further includes the steps of (g) detecting a voltage supplied by the voltage source at an every predetermined period of time, and (h) displaying a present voltage in a display screen.
It is preferable that the method further includes the step of receiving a call, when the call is of one of the stored telephone numbers, even if a voltage supplied by the voltage source is equal to or lower than a predetermined threshold voltage.
It is preferable that the step (e) includes the step of comparing each of first to N-th predetermined threshold voltages to a telephone number detected out of a received radio signal, wherein N is an integer equal to or greater than 2, and further including the step of receiving a call, if a voltage supplied from the voltage source is equal to or smaller than a M-th predetermined threshold voltage and a telephone number detected out of a received radio signal belongs to the M-th group of telephone numbers, N groups of telephone numbers being in association with each of the first to N-th predetermined threshold voltages, wherein M is an integer between 1 and N both inclusive (1xe2x89xa6Mxe2x89xa6N).
It is preferable that the method further includes the step of storing the numbers of call-receiving and call-transmitting, and wherein a call associated with the telephone number detected out of a received radio signal is determined in the step (f) to be received or not, based on at least one of the numbers of call-receiving and call-transmitting.
For instance, a call associated with the telephone number detected out of a received radio signal is determined in the step (f) to be received or not, based on a count X defined by the following equation:
X=Sxc3x97A+Rxc3x97B
wherein A indicates the number of call-receiving, B indicates the number of call-transmitting, and S and R are weight coefficients.
It is preferable that the method further includes the step of storing a total period of time during which a call is received or made, for each one of telephone numbers stored therein, and wherein a call associated with the telephone number detected out of a received radio signal is determined in the step (f) to be received or not, based on the total period of time.
The advantages obtained by the aforementioned present invention will be described hereinbelow.
In the present invention, data indicative of a telephone number of a call transmitter is detected out of a digital signal demodulated by the radio-signal processor when a call has been received, in the low-voltage mode, the detected data is compared to the telephone directory data and the characteristic data, and judgement is made as to whether a call is to be received or not. Hence, even when a source voltage is lowered in the vicinity of a lower threshold voltage, it would be possible to receive a call from a predetermined call-transmitter.
The above and other objects and advantageous features of the present invention will be made apparent from the following description made with reference to the accompanying drawings, in which like reference characters designate the same or similar parts throughout the drawings.